The problem with doing everything with our iPhones is that they just don’t have enough juice to make it through the entire day. With more apps using GPS and push notifications, that “20 percent of battery remaining” warning seems to come sooner each day. While there are some tricks to saving battery life and cases that do it for you, you may not want to deal with the hassles of changing system settings or charging a case every day. That’s where the iPhone Keychain Charger (officially the Mophie Juice Pack Reserve) comes in.

The iPhone Keychain Charger is a small external battery for iPhone. A pull-out USB plug is used to charge its 700 mAh battery and a color-changing LED indicates the battery’s charge level. The iPhone Keychain charger may only pack a 700 mAh battery (about half the capacity of the iPhone 4), but could that be enough to get you out of a sticky situation? We had some time to test it out (courtesy of Photojojo), and would like to share our impressions.

The USB plug is actually a part of the band surrounding the iPhone Keychain Charger.

The Good

Whether or not you decide to hook the battery pack to your keys is up to you. Either way, it’s more portable than most external batteries. The built-in 30 pin connector is welcome, as most external batteries require the use of your device’s charging cable. This means that you don’t need anything more than the iPhone Keychain Charger itself to charge your iPhone.

Perhaps the best thing about the iPhone Keychain Charger is its presence. That is, when you realize you need it, it’s already there (if you attached it to your keys). By now, most iPhone owners know how to manage their battery and about what time of day it will give out. The iPhone Keychain Charger is great for any unexpected situations that may require more use of your phone.

In my testing, the iPhone Keychain Charger managed to provide a 30 percent charge on average, which was more than enough to keep my phone going until I had the opportunity to use a wall or car charger.

Give your iPhone some extra juice, without the extra bulk of a battery case.

The Bad

For the same price, you can get external batteries for any USB device that hold twice the capacity of the iPhone Keychain Charger (or more).

Verdict

For the price, there are definitely more options available that will extend the life of your iDevice’s battery. However, the convenience of having the extra juice for your phone, especially if you didn’t plan ahead, makes the iPhone Keychain Charger something to be considered.

You can get the iPhone Keychain Charger for $35 from PhotoJojo, or $34.95 from Mophie.

What steps do you take to ensure your iPhone doesn’t die on you when you need it most?